Quantitative Analysis of Iron Ore
Hand-In, Chem 150L, Fall 2015
Name:
Partner:
See the attached rubric for more detailed information about grading.
1. (2 points) For the iron-phenanthroline complex that you measured the absorbance of, what color
light does the wavelength of maximum absorbance correspond to? Is this color consistent with the
color you observe? Explain using concepts developed in the introduction to spectroscopy
experiment.
{Type answer here}
2. (4 points)
a) Beer’s Law states the absorbance of a substance in solution is proportional to its concentration in
the solution. Absorbance  Concentration describes a straight line whose y-intercept is zero.
{Paste absorbance vs. concentration graph here}
b) How well does your data fit Beer’s Law?
{Type answer here}
c) What effect does this have on your confidence in your results reported below? Explain.
{Type answer here}
3. (10 points)
a) What is your unknown number? ___________
b) (4 points: accuracy) What is the percent iron (± error) in your sample? _____________________
c) (6 points) Show all calculations below. This includes the calculations for the concentration of the
standard solutions made during week 1 of this experiment. It also includes all calculations needed to
determine the %Fe2+ in the ore and the error during week 2. Use Equation editor. Show units. Be
aware of significant figures.
{Show calculations here}
4. (4 points) What specific steps in procedure or choice of equipment were taken to minimize the error
in this experiment? There were many. List and briefly discuss as many as you can.
{Type answer here}
See the attached rubric for more detailed information about grading.
Q#1
Explain
color
Q#2
Discuss
graph
Q#3b.
Accuracy
Q#3c.
Calcs.
Unsatisfactory
Illogical answer
or no answer
0 points
No graph and
no answer.
0 points
Answer within
about 30% of
the correct
answer.
1 point
Equation editor
not used.
0-1 points
Q#4
Discussion of
minimization
of error
Borderline
Graph present
but poor
discussion of
quality of data.
1-2 points
Answer within
about 20% of
the correct
answer.
2 points
2-3 points
Only 1 or 2
examples with
reasonable
discussion.
2 points
Satisfactory
3 points
Answer within
about 14% of the
correct answer.
3 points
4-5 points
Excellent
Reasonable explanation
of observed color
2 points
Reasonable discussion
of the quality of your
data and implications
for your results.
4 points
Answer within about
7% of the correct
answer.
4 points
Calculations for
standards 1 pt.,
%Fe2+ 2pts,
error 1 pt.,
Units, 1 pt.,
sig figs 1pt.
6 points
At least 3 good
examples with
reasonable discussion.
Pts.
2 pts
4 pts
4 pts
6 pts
4 pts
4 points
20
pts